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| - Salt reduces the melting point of ice by freezing-point depression, causing it to melt at lower temperatures and run off to the edge of the road, while sand increases traction by increasing friction between car tires and roadways. The amount of salt dropped varies with the condition of the road; to prevent the formation of light ice, approximately g/m² () is dropped, while thick snow can require up to g/m² () of salt, independent of the volume of sand dropped. The grit is sometimes mixed with molasses to help adhesion to the road surface. However, the sweet molasses often attracts livestock, who lick the road.
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| abstract
| - Salt reduces the melting point of ice by freezing-point depression, causing it to melt at lower temperatures and run off to the edge of the road, while sand increases traction by increasing friction between car tires and roadways. The amount of salt dropped varies with the condition of the road; to prevent the formation of light ice, approximately g/m² () is dropped, while thick snow can require up to g/m² () of salt, independent of the volume of sand dropped. The grit is sometimes mixed with molasses to help adhesion to the road surface. However, the sweet molasses often attracts livestock, who lick the road. Gritters are among the winter service vehicles also used in airports, to keep runways free of ice. However, the salt normally used to clear roads can damage the airframe of aircraft and interferes with the sensitive navigation equipment. As a result, airport gritters spread less dangerous potassium acetate or urea onto the runways instead, as these do not corrode the aircraft or the airside equipment. Gritters can also be used in hot weather, when temperatures are high enough to melt the bitumen used in asphalt. The grit or/and sand is dropped to provide a protective layer between the road surface and the tyres of passing vehicles, which would otherwise damage the road surface by "plucking out" the bitumen-coated aggregate from the road surface. Some modern gritter units also have tanks fitted for liquid urea which is used on bridge and viaduct decks to reduce corrosion of the steel work from runoff. This is to reduce long term maintenance costs, but due to the higher cost is only used in selected areas.
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